Heat exchanger for a heating device

ABSTRACT

A heat exchanger for a heating device, especially a fuel value heating device, made up of at least two vertically aligned members, and, in each case, one cover at the end face, which form a combustion chamber, and laterally border at least one heating gas flue, that leads from the combustion chamber in the upper region downwards to an exhaust collector in the lower region, having heat exchanger surfaces which, on the heating gas side, are provided with elements that increase the size of surfaces, especially in the form of ribs, optionally having at least one middle member between the two bordering outer members, and having a plurality of channels guiding the heating medium flowing through in parallel and/or in series in the members and/or the covers. The present system provides a compact heat exchanger for a heating device, and which is light and is especially suitable for the fuel value operation. In the present system, the members and the covers are connected to one another at the end face to form a block that is leak-proof to the heating gas, whose channels guiding the heating medium correspond to one another. The heat exchanger surfaces, acted upon by heating gas, of two adjacent members, over their length have a greater distance from one another in the middle, and thus form a wider heating gas flue than in the edge regions, the ribs each having a greater height in the middle and overlapping one another over a greater surface than in the edge regions.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger for a heating device.

BACKGROUND INFORMATION

There are types of heat exchanger (for a heating device) that are madeup of at least two members cast in one piece, which develop a combustionchamber having a burner connection in the upper region, as well as atleast one heating gas flue, having heat exchanger surfaces, that leadsfrom the combustion chamber to an exhaust collector in the lower region.The latter are provided with projections that are cast on, mostly ribsor knobs, for increasing the surface area so as to improve heattransmission. As a rule, the members stand vertically side by side.So-called end members, having heat exchange surfaces on only one side,form the outer limits, and may be supplemented using intermediatemembers, so as to increase the heat transmission performance. The latterhave heat exchange surfaces on both sides.

On the side of the water, up to now, all members in all specificembodiments are connected to one another via two hubs, and on theheating gas side, sealing takes place between two boiler members havingencircling packing strips, which may optionally be filled with anelastic sealing material.

In this connection, non-cooled cleaning covers, for closing channels onthe end face, that conduct heating gas, are also known, and also cooledparts, such as combustion chamber doors that have heating medium flowingthrough them. For permanent seals it is important to maintain determinedspecified values for temperature stresses in the sealing region. Besidesthe material cast iron for such heat exchangers, fuel value boilershaving a blowpipe for fossil fuels and a heat exchanger made of aluminumcasting materials are also known. These may be produced using sandcasting, extruding/die casting or sand molding casting methods. Themethods are technically of different expenditures, and are suitable ineach case for a certain number of pieces, and also have clear limits asto the design of the parts. There is a distinction between flow-forcedand non-flow-forced heat exchangers, with regard to the flow guidance onthe side of the heating medium. In flow-forced heat exchangers, acirculating pump takes care of a specified water volume flow through themostly narrow water channels that are applied in a meandering shape. Forthis purpose, heat exchanger blocks, especially cast in one piece, areknown, having water channels running around the combustion chamber andthe heating gas flue. In spite of low water contents, this makes oneable to implement rather high heating flow densities, brought in fromthe heating gas side.

In the constructive design of such an heat exchanger, the heatingperformance of the heat generator and the heat exchange surfaces, on theside of the heating gas and of the water, have to be at a certainrelationship with respect to each other. On the one hand, the heat flowof the heating gas has to be transmitted to the heat exchanger down to adesign temperature, and on the other hand, the heat exchanger has to beable to give off the same heat flow to the surrounding heating water. Ifthese two magnitudes are not adjusted to each other, this may have theresult that, either the exhaust setpoint temperature is not achieved,which becomes noticeable if there are increased exhaust gas losses, orthe overtemperature of the heat exchanger with respect to thesurrounding heating water leads to local simmering. The result will thenbe undesired simmering noises, material damage and/or deposits. It isalso known from EP 0 287 142 A2, for example, that one should design thechannel cross section for the heating medium in the entire upper zone ofthe heat exchanger block, that is hottest and close to the combustionchamber, to be narrower than in the lower, cooler region, at therecirculating water entry. Doing that is intended to achieve a high flowspeed in the channel guiding the heating medium, in the entire upper,hot region. Since the channel narrowing gradually increases over theentire course of the channel, the cooling performance also risesaccordingly.

SUMMARY OF THE INVENTION

An object of the exemplary embodiments and/or exemplary methods of thepresent invention is based on creating a compact heat exchanger for aheating device, that is light and is especially suitable for the fuelvalue operation.

According to the exemplary embodiments and/or exemplary methods of thepresent invention, this object may be attained by the features describedherein. Advantageous developments may be derived from the furtherdisclosures and descriptions herein.

The heat exchanger is characterized in that members and cover areconnected to one another at the end face to form a block that isleak-proof to the heating gas, whose channels guiding the heating mediumcorrespond to one another, and to which a burner may be connected in theupper region and an exhaust collector at the lower side.

The heat exchanger surfaces, acted upon by heating gas, in this context,of two adjacent members, over their length, in the middle, that is, atthe location of the highest thermal stress, have a greater distance fromeach other and thus form a wider heating gas flue than in the edgeregions. The ribs of two members associated with one another, in thisinstance, each have a greater height in the middle and overlap oneanother over a greater surface than in the edge regions.

For the channels guiding the heating medium in the members as well, ineach case in the middle of a member, according to the exemplaryembodiments and/or exemplary methods of the present invention, a lowercross section is also provided, so that, in that location, a higher flowspeed prevails than in the edge regions, in order to dissipate the heatfrom the hottest zone well. The cross section of the channels, guidingthe heating medium in the members, tapers in each case towards themiddle of a member, and runs conically, for example. This reduction inthe cross section essentially corresponds to the draft of the coresrequired for production by casting technology, an angle of 1.5 to 7degrees to the center axis of a channel being provided as the draft.

The channels guiding the heating medium are connected to one anotherwith the covers in such a way that, through the entire block, startingfrom a lower recirculating connection, a flowing through from below toabove sets in, to a feed connection, in counter flow to the heatinggases. The connected channels one after the other have heating mediumflowing through them, in a plurality of planes, in this instance.

In a first specific embodiment, the channels guiding the heating mediumare connected to the covers in such a way to one another that, startingfrom a recirculating connection, the following flow-through sets in:first of all, from a first lower plane via the lower region of the firstouter member, using a transfer into at least one middle member andhaving a flow-through of same in the lower region, using a transfer intothe second, outer member as well as a flow-through into its lowerregion. There then follows a U-shaped vertical deflection in the memberto a second plane in the central region, and from this, first of all, atransfer to at least one middle member and a flow through same in themiddle region, a transfer into the middle region of the first outermember, and there, a vertical turn round in the member into a thirdplane in the middle region. On this plane, the flow is reversed to thesecond plane through the entire block and guided to the second outermember. Starting from there, a U-shaped vertical deflection takes placein the member into a fourth plane in the upper region, on which a directconnecting channel exists through an end-face cover to the oppositefirst member, as well as a feed connection on the upper plane to theopposite first member, as well as a feed connection on the upper plane.

Consequently, the connecting channel includes and cools the combustionchamber on three sides, so that no insulation material is required. Onthe fourth, non-cooled side there is the possibility for access to thecombustion chamber, for instance, in the form of a recess for installingan inspection glass as well as ignition devices and/or monitoringdevices for a burner.

On the fourth plane the at least one middle member is recessed, that is,it has one cooling channel less than the two outer members, in order toform a somewhat lower combustion chamber or to assure the necessarycombustion height.

In a second specific embodiment, the channels guiding the heating mediumare connected to one another using the covers in such a way that,starting from the recirculating connection, a serpentine-likeflow-through sets in in the first outer member, a transfer and also aserpentine-like flow-through sets in in at least one middle member, anda transfer and a serpentine-like flow-through sets in in the secondouter member having a connection to a feed connection.

Deflection zones are generally provided in the covers, which are made upof arches of the walls bordering the deflection zones. In the deflectionzones, the channels guiding the heating medium have at least an equallygreat, or a greater cross section than in the end regions of themembers, so as to take care of a calmed flow deflection that has littlepressure loss. In the upper region, the cover may have no channelsguiding the heating medium, but has instead a recess for installing aninspection glass as well as ignition devices and/or monitoring devicesfor a burner. In order to connect all components to one block in amanner that is leak-proof to heating gas and liquid, the end faces ofthe members are developed like a flange, and form a contact surface anda sealing surface for an associated cover. The covers are advantageouslyconnected to the members via a friction welding method, but otherwelding connection methods suitable for aluminum materials are alsoconceivable for this purpose. Covers may also be screwed together attheir two outer edges at several points to the two outer members.

Furthermore, the elements enlarging the surfaces in the heating gas fluemay be horizontally interrupted, especially in the form of ribs runningin the vertical direction. This interruption is intended to prevent heatconduction from the hot, upper region into the cooler, lower heatexchanger surface region, for instance, in order optimally to cool theheating gases below the dew point and to utilize the fuel value. Theinterruption of a rib in each case takes place at least in the regionbetween the first and the second plane of the channels guiding theheating medium, which already have a clear temperature difference withrespect to each other. In addition, a venting nozzle, a gas/air mixturesupply line and/or an exhaust gas line may be integrated into a memberor a cover.

The exemplary embodiments and/or exemplary methods of the presentinvention provides a compact heat exchanger that is light and especiallysuitable for fuel value operation for a heating device, that is madeprimarily of aluminum casting materials. A modular construction forrepresenting different performance sizes is easily possible, and theproduction of boiler members is relatively favorable. The heat exchangeris easy to clean and is accessible starting from the upper side, via therelatively large combustion chamber. The aluminum parts may be producedin mass production using easily formable cores in sand casting andextruding/die casting methods or in sand molding casting methods.

This design according to the exemplary embodiments and/or exemplarymethods of the present invention has the advantage that the heattransfer coefficient is the greatest at the center of the heatexchanger. Because of the tapering water channels, the speed of theheating medium is relatively low at the beginning and the end of eachchannel. It is only high in the center, where a high heat transmissionperformance is required. Therefore, the channels guiding the heatingmedium are able to become narrower, and the height of the ribs mayincrease correspondingly, because the high heat input at the center isable to be transferred to the heating medium easily because of thelocally higher speed. The otherwise usual problem of the danger ofboiling at this critical location is voided.

The efficiency of the heat exchanger is increased especially on the sideof the heating gas, because the ribs are interspersed among one another,and thus offer a large specific heat exchanger surface. Furthermore, inthe design according to the exemplary embodiments and/or exemplarymethods of the present invention, relatively low temperatures prevail inthe sealing zones having heating medium flow around them, which makespossible the use of common sealing materials.

The drawings represent an exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a heat exchanger in a perspective view.

FIG. 2 shows a heat exchanger in a perspective exploded view.

FIG. 3 shows a heat exchanger in a horizontal longitudinal section.

FIG. 4 shows a heat exchanger in a vertical longitudinal section.

DETAILED DESCRIPTION

The heat exchanger is made up essentially of two vertically alignedouter members 1, 1′, two middle members 2 positioned between the latter,as well as a cover 3, 3′ in each case at the end faces. This forms acombustion chamber 4 in the upper region, beginning from which heatinggas flues 5 having heat exchanger surfaces furnished with ribs 6 lead toan exhaust collector, that is not shown, in the lower region.

Channels 7 guiding heating medium are integrated into all members 1, 1′,2 and covers 3, 3′, so that, via covers 3, 3′, at the end face, allmembers 1, 1′, 2 are mounted, to form a block that is leak-proof toheating gas, and with regard to channels 7 guiding the heating medium,is at least partially connected.

From FIG. 3 especially it may be inferred how the heat exchangersurfaces of two adjacent members 1, 1′, 2, over their length have agreater distance from one another in the middle, and thus form a widerheating gas flue 5 than in the edge regions. In FIGS. 3 and 4 one maysee, moreover, that the cross section of channels 7 guiding the heatingmedium is reduced in size conically, in members 1, 1′, 2, in each casegoing towards to middle of a member 1, 1′, 2, in order to achieve agreater flow speed there than in the edge region.

The channels 7 guiding the heating medium having the covers 3, 3′, areconnected to one another in such a way that, through the entire block,starting from a lower recirculating connection, a flowing through frombelow to above sets in to a feed connection that is mounted there, incounter flow to the heating gases. In this context, the channels 7guiding the heating medium have it flowing through them in severalplanes E1, E2, E3, E4, one after the other. In each case, within oneplanes E1, E2, E3, E4, the flow snakes through the components of thesystem, at a horizontal deflection in deflection zones 8 of covers 3,3′. At the end of the flow path, in a planes E1, E2, E3, alternatelywithin the two outer members 1, 1′, there takes place a U-shapedvertical deflection 8′ up to the next planes E2, E3, E4 lying above it.

In the upper region, cover 3′ has no channels 7 guiding the heatingmedium, but has instead a recess 9 for installing an inspection glass aswell as ignition devices and/or monitoring devices for a burner. The endfaces of all members 1, 1′, 2 are developed flange-like, and form acontact surface and sealing surface for an associated cover 3, 3′, thecovers 3, 3′ being connected either using a welding method or, at theirtwo outer edges, being screwed together at several points 10 with thetwo outer members 1, 1′.

In FIG. 1 a venting nozzle 11 is also shown, that is integrated intocover 3.

1-14. (canceled)
 15. A heat exchanger for a heating device, comprising:a plurality of elements that increase a surface size; and at least twovertically aligned members, each having a cover at an end face, whichform a combustion chamber, and which laterally border at least oneheating gas flue, that leads from the combustion chamber in an upperregion downwards to an exhaust collector in a lower region, having heatexchanger surfaces, which, on a heating gas side, have the plurality ofelements that increase the surface size, which are in the form of ribs,and having a plurality of channels guiding a heating medium flowingthrough at least one of in parallel and in series at least one of in themembers and the covers; wherein the members and the covers are connectedto one another at the end face to form a block that is leak-proof to theheating gas, whose channels, which guide the heating medium, correspondto one another.
 16. The heat exchanger of claim 15, wherein the heatexchanger surfaces, acted upon by the heating medium, which is a heatinggas, of two adjacent members, over their length have a greater distancefrom one another in the middle, and thus form a wider heating gas fluethan in the edge regions, the ribs each having a greater height in themiddle and overlapping one another over a greater area than in the edgeregions.
 17. The heat exchanger of claim 15, wherein the channelsguiding the heating medium in the members each have a smaller crosssection in the middle of a member and have a higher flow speed than inthe edge regions.
 18. The heat exchanger of claim 15, wherein the crosssection of the channels guiding the heating medium in the members eachtapers down towards the middle of a member.
 19. The heat exchanger ofclaim 15, wherein a cross section of the channels guiding the heatingmedium, that diminishes towards the middle, essentially corresponds to adraft of the cores required for the production by casting technology,and wherein an angle of 1.5 degrees to 7 degrees with respect to acenter axis of a channel is provided.
 20. The heat exchanger of claim15, wherein the channels guiding the heating medium are connected to oneanother with the covers so that, through the entire block, starting froma lower recirculating connection, a flowing-through from below to abovesets in to a feed connection that is mounted there, in counter flow tothe heating gases; and the channels guiding the heating medium areconnected to one another so that a plurality of planes have it flowingthrough them one after another.
 21. The heat exchanger of claim 15,wherein the channels guiding the heating medium are connected to thecovers in such a way to one another that, starting from a recirculatingconnection a flow-through sets in, which exists first from a first lowerplane via the lower region of the first outer member, a transfer into atleast one middle member and a flowing through of the same in the lowerregion, a transfer into the second outer member and a flowing through inits lower region, wherein at that point there takes place a U-shapedvertical turn round in the member to a second plane into the middleregion, and from this, a transfer into at least one middle member and aflow-through of same in the middle region, a transfer into the middleregion of the first outer member, and there, a vertical turn round inthe member into a third plane in the middle region, on this plane theflow being reversed to the second plane through the entire block andguided into the second outer member, and wherein and starting fromthere, a U-shaped vertical turn round takes place in the member into afourth plane in the upper region, on which there exists a directconnecting channel through an end face cover to the opposite firstmember and to a feed connection on the upper plane.
 22. The heatexchanger of claim 15, wherein the channels guiding the heating mediumare connected to the covers so that, starting from a recirculatingconnection, a serpentine-like flow-through sets in in the first outermember, a transfer and also a serpentine-like flow-through sets in in atleast one middle member and a transfer and a serpentine-likeflow-through sets in in the second outer member having a connection to afeed connection.
 23. The heat exchanger of claim 15, wherein horizontalturn round zones and vertical turn round zones are in the covers and aremade up of arches of the walls bordering on the turn round zones. 24.The heat exchanger of claim 23, wherein the channels guiding the heatingmedium in the turn round zones have an at least equally large or alarger cross-section than in the edge regions of the members.
 25. Theheat exchanger of claim 15, wherein in the upper region, a cover has nochannels guiding the heating medium, and wherein the cover has a recessfor installing an inspection glass and at least one of an ignitiondevice and a monitoring device for a burner.
 26. The heat exchanger ofclaim 15, wherein the end faces of the members are flange-like and forma contact surface and sealing surface for an associated cover, andwherein the covers are connected at their two outer edges, at severalpoints, to the two outer members.
 27. The heat exchanger of claim 15,wherein the elements enlarging the surfaces in the heating gas flue arehorizontally interrupted, and are in the form of the ribs running in thevertical direction, in each case at least in the region between thefirst plane and the second plane of the channels guiding the heatingmedium.
 28. The heat exchanger of claim 15, wherein at least one of aventing nozzle, a gas/air mixture supply line and an exhaust gas lineare integrated into one of a member and a cover.
 29. The heat exchangerof claim 15, wherein the heating device is a fuel value heating device.30. The heat exchanger of claim 15, further comprising: at least onemiddle member between two bordering outer members.